Fire-alarm transmitter



(No Model.)

W. 0. S HAFFER.

FIRE ALARM TRANSMITTER.

PatentedApr. 6, 1886.

UNITED STATES PATENT OFFICE.

IYILLIAM C. SHAFFER, OF CHICAGO, ILLINOIS.

FIRE-ALARM TRANSMITTER.

SPECIFICATIQN forming part of Letters Patent No. 339,485, dated April 6,1886 Application filed August 24, 1885. Serial No. 175,132. (No model.)

To all whom, it may concern:

Be it known that I, WILLIAM C. SHAFFER, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Fire-Alarm Transmitters;and I do hereby declare the following to be a full, clear, and exactdescription of the invention, such as will enable others skilled in theart to which it appertains to make and use the same, reference being hadto the accom' panying drawings, and to letters or figures of referencemarked thereon, which form a part of this specification.

This invention relates to fire-alarm transmitters, by which an alarm ofabnormal heat is sent over an electric or other equivalent line to adistant station, and has special reference to such transmitters in whichthe send ing of the signal is dependent upon the melting or partialmelting of a material whose melting-point is approximately equal to thetemperature of which it is desired to give notice.

In the accompa'nyiug drawings, Figure 1 is a plan of one of my improvedtransmitters. Fig. 2 is a plan of the same with the cover removed. Fig.3 is a side elevation when the cover is removed. Fig. a is a verticalsection through the center of the transmitter. Fig. 5 shows amodification of the instrument.

A is a base of wood or other material, upon which the operatingmechanism is mounted.

B B are binding-posts, for securing the circuitwires C C.

D is a yielding electrode or pole, electrically connected with thebindingpost B.

D is a swiveled bar electrode, electrically connected with thebindingpost B, and having one end adapted to move into or out of contactwith the free end of the electrode D. This bar may be made in a varietyof forms. In the drawings one end thereof is in the form of a segment ofa circle, having teeth (2 on the periphery, while the other end has aneye, and the middle thereof is loosely pierced by the vertical screw orpost 01, which latter is firmly seated in the base A, and electricallyconnected with the binding-post B.

E is a spring, attached by one end to the base A,and by the other to thebar D, at the end opposite the point of contact. Said spring,

when unhindered, turns the bar D in the direction of the arrow in Fig.2.

It will readily appear that when the bar D is moved or rotated about thepost d the circuit will be made and broken as many times as there areteeth on said bar, and that the contacts will be made by the teeth (1sliding over the surface of the electrode D, thereby pushing aside anyforeign matter on the contactpoints and insuring a closing of thecircuit. By using a series of teeth, d, each designed to make a circuitin its turn, I am the more certain of making the circuit, for if aportion of the teeth should fail I can rely on the others.

Instead of arranging the teeth in a regular series,- they may be groupedafter the manner of a recording-telegraph, in order that the number ofthe heated transmitter may be sounded or recorded at the station. Whenthese teeth are thus grouped, or when they are arranged in a regularseries, it is essential that the bar D move slowly and with anapproximatelynniform motion, in order that the breaking and making, andmaking and breaking, of the circuit may be sufficiently slow to allowthe sounding or recording mechanism at the station to act.

In preparing the transmitter for action I turn the bar D to its farthestlimit in the direction opposite that indicated by the arrow, and thenplacea mass of fusible retarding material, F, consisting of rosin,shellac, or other substance which melts at the desired temperature, andwhich becomes viscous on melting, on the surface of the base A, in frontof the bar D. This mass of fusible material retains the bar D inposition until the melting heat is reached, whereupon it softenssufficiently to allow the bar D to move slowly under the pressure of thespring E. Any material which would promptly liquefy on melting would ofcourse allow the bar to move instantly. Therefore for my purpose I avoidthe use of such material.

In experimenting I have found that in some situations the rosin orshellac F will yield prematurely to the pressure of the spring E. Insuch cases I re-euforce the rosin or shellac with a plug, F, made of alow-fusion metal alloy. Such plug holds the bar D positively until thechosen temperature is reached, whereupon it yields abruptly and allowsthe rosin or shellac to retard or govern the movement of the bar.

G is a cover, having in its face the holes g, and about itscircumference the flange g to embrace the base A. Said cover serves as aprotection for the inner mechanism, and the holes 9 serve to facilitatethepassage of heat to the fusible material within. Said cover may beimmovably attached to the base A; but

I prefer to secure it thereto by a readily-fusible material, G, in orderthat the cover may be released and allowed to fall by its gravity,

the transmitter being usually attached to the ceiling with said coverdirected downward, thus more effectually exposing the inner mechanism tothe heat. It is desirable, also, to have these covers fall, in order toreadily show which particular transmitter was sufficiently heated togive an alarm.

It is obvious that in most cases the material G will melt and yieldbefore the material F will, even when the two are of the same kind, forthe reason that the material G is first exposed to the heat; but if itis desired to hasten the fall of the cover, the material G may be madeof a lower melting point than the materials F and F.

In this class of instruments oxidation and corrosion frequentlyinjurethe metallic parts, and particularly the contact-points and the alloyplugs, the latter sometimes becoming harder and sometimes softer, andsometimes raising and sometimes lowering (depending upon the ingredientsof the alloy) its meltingpoint. In many cases the transmitters must belocated in moist places and places abounding in corrosive gases,wherethe oxidation and corrosion are a constant annoyance. To overcome this,I take the transmitter when set ready for action and dip it into liquidparafiine. This covers every part with a layer which is proof againstthe action of these destructive agents, and which is so much softened byabnormal heat as to allow the free action of the movable parts of thetransmitter. As the parafline is a non-conductor, it can in no wayinterfere with the circuit.

The instrument is usually attached, face downward, to the ceiling, butit may obviously be placed in other positions. It is obvious, also, thata weight may in some cases be substituted for the spring E. In Fig. 5the bar D is itself weighted and so mounted as that it will move ofitself when the material F has become sufficiently softened.

I claim as my invention- 1.' The combination of a movable multicontactelectrode and a fusible plug applied directly to said electrode,substantially as shown and described.

2. The combination of a movable electrode and a retarding material forcontrolling the movement of said electrode, substantially as shown anddescribed.

3. The combination of a movable electrode, a spring or weight to actuatesaid electrode, and a mass of material which is normally solid and holdssaid electrode out of action, but which becomes viscous or semi-solidfrom abnormal heat, whereby the electrode is retarded in its movement,substantially as shown and described.

4. The combination of a. movable multicontact electrode, a spring orweight to actuate said electrode, and a mass of material which isnormally solid and holds said electrode out of action, but which becomesviscous or semi -solid from abnormal heat, whereby the electrode isretarded in its movement, substantially as shown and described.

5. The combination of a movable electrode, a spring or weight to actuatesaid electrode, and a mass of material which under abnormal heat changesabruptly from the solid to the liquid form, and a material which becomesplastic or viscous under abnormal heat, substantially as shown, and forthe purpose set forth.

6. The combination of a movable multicontact electrode, a spring orweight to actuate. said electrode, and a mass of material which underabnormal heat changes abruptly from the solid to the liquid form, and amaterial which becomes plastic or viscous under abnormal heat,substantially as shown,and for the purpose set forth.

7. The combination of the base A, electrodes D D, spring E, and materialF, which becomes viscous or plastic under abnormal heat, substantiallyas shown and described.

8. The combination of the base A, electrodes D D, spring E, material F,which becomes viscous or plastic under abnormal heat, and the alloy F,which changes abruptly from the solid to the liquid state, substantiallyas shown, and for the purpose described.

9. The combination of a movable electrode,

an alloy plug to stay said electrode, and an oxidation and corrosionproof coating for said alloy plug, substantially as shown and described.

ICO

fall, thereby more effectually exposing said a transmitter to the actionof the heat, substantially as shown and described.

12. The combination, with the base A, electrodes D D, spring E, andfusible material F, of a cover, G, held in place by a ma- .WILLIAM C.SHAFFER.

Witnesses:

OYRUs KEHR, CHARLES H. ROBERTS.

